Keeping calves longer on milk helps ensure the rumen is developed well enough to absorb important nutrients.
By the time ruminants are weaned, it’s imperative that rumen epithelia are functioning optimally to ensure the proper absorption of volatile fatty acids (VFA) into the blood stream.
Why it matters: Better absorption of nutrients after weaning means that calves will grow faster and make better use of feed.
“When calves are born, the rumen is extremely underdeveloped and does not yet possess the capacity to transport the necessary VFAs to grow the animal,” says Dr. Anne Laarman of the University of Alberta during the virtual Animal Nutrition Conference of Canada.
Laarman says the research has been conducted in both dairy and beef calves and applies to both.
When calves are removed from milk too early, issues arise quickly.
“The (calf) starter intake is not yet high enough to compensate for that lack of energy. That total digestible energy goes down and as a result you actually see considerably less growth.”
Reducing the milk provision early reduces digestible energy intake and growth.
“We have a very vested interest in making sure that rumen is developed properly before we start relying on it for nutrient absorption,” says Laarman.
A study completed at the University of Guelph in 2015, by Eckert et al., showed that calves weaned at six weeks had a huge drop in digestible energy at weaning. The drop in digestible energy intake for calves weaned at eight weeks was a fraction of what it was when they were weaned at six weeks.
“When we are weaning prematurely and removing that milk content entirely, it also reduces digestible energy intake,” says Laarman.
As ruminants begin on a liquid diet — milk or milk replacer – they are reliant on glucose as a substrate and its absorption through the small intestine. As they graduate onto solid feed VFAs are important and are absorbed through the rumen.
Within the first couple of months, VFA absorption is heavily related to intracellular pH regulation.
There are two major factors — supplementation and management — that help set up calves for success in VFA absorption
“Butyrate supplementation during the weaning transition only in week seven and eight increases calf starter intake.”
Following the removal of the sodium butyrate supplementation at week nine, the calf starter intake continues to increase at 800 grams per day.
As well, butyrate supplementation corresponded with an increase in VFA absorption.
“Butyrate supplementation is one of the more common strategies in improving calf rumen development and improving the VFA absorption capacities.”
As well, supplementation of amino acids glutamine, glutamate and arginine are important.
“The reason they are important is because they are the preferred energy substrate for the small intestine.”
The large intestine and the rumen prefer butyrate as their energy substrate.
Within the first few months of life numerous stressors are encountered. It’s important to isolate these different stressors as a management factor to improve gut health and rumen development within the first few months of life.
“Typically when the calves are born, dairy calves are removed from their mother. In beef calves they are not, (but) when they are weaned, they are not just weaned but they are also moved to a new location.”
As well, once weaned, they may have a different diet and entirely different feed sources. It’s important to isolate these stressors to ensure only one is happening at a time.
“If you are running a cow calf operation and you send your calves to a feedlot or backgrounding operation, don’t feed them milk right up until the day they load in the truck.”